1. Field of the Invention
This invention relates to a method for producing a three-dimensional laminated object such as casting molds by piling solid layers formed by use of a laser beam.
2. Description of the Related Art
A technique has been developed recently for producing a three-dimensional laminated object. It is disclosed in Japanese Unexamined Patent Publication (KOKAI) No.3-183,530 and U.S. Pat. No, 4,247,508. This technique emits a laser beam to material such as resin-coated sand to form a solid layer, piling a plurality of solid layers in a thickness direction to produce the three-dimensional laminated object.
This technique emits the laser beam to the material so as to obtain a target shape, forming convex portions 101a being equivalent to a diameter of the laser beam in a skin portion 101 of the solid layer 100, as appreciated in FIG. 16. Since the diameter of the laser beam influences shape-accuracy of the skin portion 101 in such a way, the diameter is set to be small. So, this technique has a limit in increasing an irradiation area, requiring a long irradiation time for forming one solid layer, thereby generating a limit in productivity of the three-dimensional laminated object.